Collagen is the most abundant protein in humans, comprising 1/3 of the total protein and 3/4 of the dry weight of skin. Collagen abnormalities are associated with many human diseases, including arthritis. The long-term objective of the proposed research is to reveal in atomic detail the chemical basis for the unique triple-helical structure of collagen, and to devise new therapies based on that knowledge. Specific Aims. The five Specific Aims of this research proposal apply methods and ideas from physical organic chemistry, peptide chemistry, molecular self-assembly, chemical enzymology, and matrix biology. Aim 1 is to assess the contribution of fundamental physicochemical forces to triple-helix stability. Aim 2 is to test the hypothesis that a newly revealed force-the hyperconjugative n* interaction-links the backbone atoms in a polypeptide chain and thereby contributes to the conformational stability of collagen-related structures. Aim 3 is to create collagen fragments and strands that self-assemble into human-scale triple helices. Aim 4 is to gain insight into the mechanism of catalysis by human prolyl 4-hydroxylase, which is the enzyme that installs the prevalent and important 4-hydroxyproline residues in collagen strands. Finally, Aim 5 is to use extant knowledge of collagen to develop a new means to assess and heal pathologic wounds in an animal. Significance: The results of the research proposed herein will provide fundamental insights into the structure and conformational stability of the collagen triple helix, and will use those insights to create collagen mimics and collagen-based biomaterials with important therapeutic applications. PUBLIC HEALTH RELEVANCE This research project is focused on collagen, which is the most abundant protein in humans. Collagen abnormalities are associated with a variety of human diseases, including arthritis. The goal of the project is to obtain insights into the relationship between the amino acid sequence of collagen and its biological function (or dysfunction), as well as to create novel collagen-like proteins of potential therapeutic use.